NOTE:
The radio frequency energy radiated by a transmitting antenna is
a form of electricity. Severe burns or shock can be received if
you make contact with the antenna while it is transmitting. All
personnel should be trained to avoid contact with an antenna
while a transmission is being made.
6.
RADIATION PATTERNS.
The energy of radio signals radiated by an
antenna forms an electromagnetic field which moves outward from the antenna
(Figure 4) much like the waves created when a stone is dropped into a calm
pond. Figure 5 graphically portrays this action. As the stone is dropped
into the water (Fig 5 (A)) and strikes the surface, the water is pushed
outward and upward, imparting an initial velocity to the mass of water at
the point of disturbance (Fig 5 (B) and (C)). The leading wave continues to
move outward and is followed by a series of waves of decreasing amplitude
and velocity.
Notice that these waves have amplitude (Fig 5 (A)) and
wavelength (Fig 5 (B)).
Figure 5.
Wave motion on a water surface.
7
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